1. Field of the Invention
This invention relates to a process for making surfactant mixtures having a relatively high solids content.
2. Description of the Related Art
Surfactant manufacturers normally seek to prepare their products having as great a solids concentration as possible in order to minimize transportation costs. However, it not always possible to take advantage of such economic benefits when mixtures containing the sodium salts of certain surfactants are being shipped because of the difficulty in preparing such mixtures in highly concentrated form. For example, surfactant mixtures comprised of 25% by weight of the sodium salt of an alcohol sulfate and 25% by weight of an alkyl polyglycoside cannot be made by the conventional method of mixing aqueous solutions of the two components because the water solubility of an alcohol sulfate in water is about 30% by weight while the maximum solubility of a fatty alkyl polyglycoside in water can be up to about 65% by weight. Therefore, it would be impossible to make a surfactant mixture containing an alkyl polyglycoside and having 30% by weight of, for example, sodium lauryl sulfate by simply mixing a 30% aqueous sodium lauryl sulfate solution and an aqueous alkyl polyglycoside solution. Such solubility limitations are not encountered with the corresponding ammonium salts of neutralizable surfactants. Therefore, mixtures containing high concentrations of such ammonium salts are obtainable by mixing highly concentrated solutions. In order to minimize the costs of shipping a highly concentrated surfactant mixture, such as one containing sodium lauryl sulfate and an alkyl polyglycoside, a manufacturer would strive to make a surfactant mixture having as little water as possible. The present invention is a method for making a relatively highly concentrated surfactant mixture containing an anionic surfactant and an alkyl polyglycoside regardless of whether or not the anionic surfactant is available itself in a highly concentrated form. The process according to the invention is particularly useful for preparing relatively highly concentrated surfactant mixtures containing the sodium salts of moderately soluble anionic surfactants and alkyl polyglycosides.